Investigation of Crystal Defects in Lead Zirconate Titanate Films by Thermally Stimulated Current Measurement

Pb(Zr, Ti)O3 (PZT) ferroelectric thin films have been extensively investigated because of their potential for FeRAM and MEMS device applications. However, realization of high performance devices has not been achieved due to degradation problems for the PZT films, such as fatigue and imprinting. The degradation is caused by crystal defects in the films, however, properties of the defects have not yet been sufficiently clarified. We have therefore attempted to investigate crystal defects in PZT films by thermally stimulated current (TSC) measurements. Current peaks due to the defects were detected in the measurements, and the origin of the observed defects was identified by systematic evaluation. It was revealed that the activation energy of the TSC peaks ranged from 0.75 eV to 0.95 eV, and the peaks were related to PbOx defects at the interface between the electrodes and the PZT layer.